Brown chicken in oil in a saute pan over medium-high heat, 23 minutes per side.,Remove chicken to a plate.,Add onion, garlic, oregano, chili powder, cumin, coriander, salt, and cayenne to the pan; cook 23 minutes.,Stir in tomatoes, scraping up browned bits from chicken; bring mixture to a boil.,______,slow cooker.,Add reserved chicken and drippings.,Cover slow cooker and cook 34 hours on high setting, or 67 hours on low setting.,Remove chicken to a plate; let rest 5 minutes.,Shred chicken into strips.,Puree tomato mixture in slow cooker with a handheld blender; stir in lime juice and season with salt.,Reserve 1 cup sauce, then toss chicken with remaining sauce.,Serve chicken in tortillas with Pepper Salad, guacamole, sour cream, and reserved sauce.